Monthly Archives: February 2009

Accelerometers are tools kinesiologists and exercise physiologists use to objectively monitor physical activity in individuals. This has generally been done with children and younger people with little attention given to older adults. A group of researchers at the University of Lethbridge in Alberta used accelerometers on 38 participants (15 males, 18 females) aged between 66 and 72 years to come up with a profile of older adult physical activity levels. They found that average time spent in light activity was the same for both males and females (just under 14 hours) but women spent less time being sedentary (7.4 hrs vs. 8.9 hrs). They also determined that the number of minutes spent in moderate to vigorous physical activity was greater in men (75 min vs. 60 min), however, the number of minutes spent in sporadic activity (bouts of under 10 minutes) was about the same (approx. 50 minutes).

Short bouts (10-19 min) and longer bouts (>20 minutes) have previously been shown to have the best cardio-vascular health benefits. For both genders, longer bouts of activity occurred in the morning and in general, more time spent in low-intensity physical activity increased with age. Thus, the researchers concluded that interventions targeted at older adults should be aimed at increasing time spent in moderate to vigorous physical activity and decreasing time spent being sedentary.

A team of researchers at the University of Sydney, Australia sought to determine whether the intensity of explosive resistance training enhances the contribution that muscle force and contraction speed make to improving peak power.

Peak power is the power output produced for a relative intensity (as determined by a percentage of the maximum intensity someone can reach during resistance training–the so-called 1RM). Traditional resistance training is high-intensity but slow speed or velocity and has been proven to improve muscle strength. Explosive resistance-training, on the other hand, uses a high load as well but it is lifted as quickly as possible. This has also been determined to be effective in increasing muscle strength. The researchers studied 112 healthy older adults between ages 63 and 75 divided into 3 training intensity groups: low-, medium-, and high-intensity explosive training. All groups trained for 8-12 weeks, twice a week. They concluded that improvements in peak power resulted mainly from improvements in force rather than speed. Further, they corroborated their earlier findings, that high-intensity training best improved muscle strength and endurance but low-intensity best improved balance performance. All three levels of intensity seem to have the same relative effect on peak performance.

To your health,

Chris

References

de Vos, N.J., Singh, N.A., Ross, D.A., et al. (2008). Effect of Power-Training Intensity on the Contribution of Force and Velocity to Peak Power in Older Adults. Journal of Aging and Physical Activity, 16(4), 393-407.

Argentine Tango-dancing and traditional walking programs were compared recently in their effectiveness in improving balance and walking confidence in a group of older adults at risk of falling

The study at McGill University in Montreal randomly assigned 30 people aged 62 to 69 into two groups, all of whom had previously fallen and were at risk of falling again. One group underwent a 10-week walking program and the other took tango-dancing lessons for the same period of time. After completing their respective programs, the participants were assessed using an Activities-based Balance Confidence (ABC) scale, sit-to-stand test, and had their normal and fast walking speeds recorded to determine if improvements were made in their balance and walking confidence and which of the two programs was most effective.

Participants in both groups made improvements in all tests after the 10-week programs were finished and continued to maintain their improvements at the 1-month follow-up. However, greater gains were made in sit-to-stand speed (a measure of lower body strength) in the tango group. This also occurred in the results on the ABC scale. Normal and fast walking speeds improved for both groups where the improvement was about the same after the 10-week period but that benefit was slightly higher for the tango group when the participants were tested at the 1-month follow-up. The researchers could not assume, however, that the improvements in balance and confidence in the walking group would necessarily translate to lower risk of falling because their baseline scores were already higher than the cut-off point set for improvements to fall risk.

Still the researchers felt that adding tango classes to an arsenal of physical activity programs designed to improve balance and walking confidence was a good way to help reduce the risk of falls in older adults since the seniors who participated in the study continued to take the classes after the follow-up period. The classes were clearly popular with the participants.